Annotation of src/usr.bin/ssh/buffer.c, Revision 1.33
1.33 ! djm 1: /* $OpenBSD: buffer.c,v 1.32 2010/02/09 03:56:28 djm Exp $ */
1.1 deraadt 2: /*
1.3 deraadt 3: * Author: Tatu Ylonen <ylo@cs.hut.fi>
4: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5: * All rights reserved
6: * Functions for manipulating fifo buffers (that can grow if needed).
1.6 markus 7: *
1.8 deraadt 8: * As far as I am concerned, the code I have written for this software
9: * can be used freely for any purpose. Any derived versions of this
10: * software must be clearly marked as such, and if the derived work is
11: * incompatible with the protocol description in the RFC file, it must be
12: * called by a name other than "ssh" or "Secure Shell".
1.3 deraadt 13: */
1.1 deraadt 14:
1.29 stevesk 15: #include <sys/param.h>
1.28 stevesk 16:
1.30 stevesk 17: #include <stdio.h>
1.28 stevesk 18: #include <string.h>
1.31 deraadt 19: #include <stdarg.h>
1.1 deraadt 20:
21: #include "xmalloc.h"
22: #include "buffer.h"
1.10 markus 23: #include "log.h"
1.1 deraadt 24:
1.27 djm 25: #define BUFFER_MAX_CHUNK 0x100000
26: #define BUFFER_MAX_LEN 0xa00000
27: #define BUFFER_ALLOCSZ 0x008000
28:
1.1 deraadt 29: /* Initializes the buffer structure. */
30:
1.6 markus 31: void
1.2 markus 32: buffer_init(Buffer *buffer)
1.1 deraadt 33: {
1.18 markus 34: const u_int len = 4096;
35:
36: buffer->alloc = 0;
37: buffer->buf = xmalloc(len);
38: buffer->alloc = len;
1.2 markus 39: buffer->offset = 0;
40: buffer->end = 0;
1.1 deraadt 41: }
42:
43: /* Frees any memory used for the buffer. */
44:
1.6 markus 45: void
1.2 markus 46: buffer_free(Buffer *buffer)
1.1 deraadt 47: {
1.18 markus 48: if (buffer->alloc > 0) {
49: memset(buffer->buf, 0, buffer->alloc);
1.19 markus 50: buffer->alloc = 0;
1.33 ! djm 51: free(buffer->buf);
1.18 markus 52: }
1.1 deraadt 53: }
54:
1.4 markus 55: /*
56: * Clears any data from the buffer, making it empty. This does not actually
57: * zero the memory.
58: */
1.1 deraadt 59:
1.6 markus 60: void
1.2 markus 61: buffer_clear(Buffer *buffer)
1.1 deraadt 62: {
1.2 markus 63: buffer->offset = 0;
64: buffer->end = 0;
1.1 deraadt 65: }
66:
67: /* Appends data to the buffer, expanding it if necessary. */
68:
1.6 markus 69: void
1.14 stevesk 70: buffer_append(Buffer *buffer, const void *data, u_int len)
1.1 deraadt 71: {
1.14 stevesk 72: void *p;
73: p = buffer_append_space(buffer, len);
74: memcpy(p, data, len);
1.1 deraadt 75: }
76:
1.27 djm 77: static int
78: buffer_compact(Buffer *buffer)
79: {
80: /*
81: * If the buffer is quite empty, but all data is at the end, move the
82: * data to the beginning.
83: */
84: if (buffer->offset > MIN(buffer->alloc, BUFFER_MAX_CHUNK)) {
85: memmove(buffer->buf, buffer->buf + buffer->offset,
86: buffer->end - buffer->offset);
87: buffer->end -= buffer->offset;
88: buffer->offset = 0;
89: return (1);
90: }
91: return (0);
92: }
93:
1.4 markus 94: /*
95: * Appends space to the buffer, expanding the buffer if necessary. This does
96: * not actually copy the data into the buffer, but instead returns a pointer
97: * to the allocated region.
98: */
1.1 deraadt 99:
1.14 stevesk 100: void *
101: buffer_append_space(Buffer *buffer, u_int len)
1.1 deraadt 102: {
1.17 deraadt 103: u_int newlen;
1.14 stevesk 104: void *p;
105:
1.23 markus 106: if (len > BUFFER_MAX_CHUNK)
1.16 markus 107: fatal("buffer_append_space: len %u not supported", len);
108:
1.2 markus 109: /* If the buffer is empty, start using it from the beginning. */
110: if (buffer->offset == buffer->end) {
111: buffer->offset = 0;
112: buffer->end = 0;
113: }
114: restart:
115: /* If there is enough space to store all data, store it now. */
116: if (buffer->end + len < buffer->alloc) {
1.14 stevesk 117: p = buffer->buf + buffer->end;
1.2 markus 118: buffer->end += len;
1.14 stevesk 119: return p;
1.2 markus 120: }
1.27 djm 121:
122: /* Compact data back to the start of the buffer if necessary */
123: if (buffer_compact(buffer))
1.2 markus 124: goto restart;
1.27 djm 125:
1.2 markus 126: /* Increase the size of the buffer and retry. */
1.27 djm 127: newlen = roundup(buffer->alloc + len, BUFFER_ALLOCSZ);
1.23 markus 128: if (newlen > BUFFER_MAX_LEN)
1.16 markus 129: fatal("buffer_append_space: alloc %u not supported",
1.17 deraadt 130: newlen);
1.25 djm 131: buffer->buf = xrealloc(buffer->buf, 1, newlen);
1.17 deraadt 132: buffer->alloc = newlen;
1.2 markus 133: goto restart;
1.14 stevesk 134: /* NOTREACHED */
1.27 djm 135: }
136:
137: /*
138: * Check whether an allocation of 'len' will fit in the buffer
139: * This must follow the same math as buffer_append_space
140: */
141: int
142: buffer_check_alloc(Buffer *buffer, u_int len)
143: {
144: if (buffer->offset == buffer->end) {
145: buffer->offset = 0;
146: buffer->end = 0;
147: }
148: restart:
149: if (buffer->end + len < buffer->alloc)
150: return (1);
151: if (buffer_compact(buffer))
152: goto restart;
153: if (roundup(buffer->alloc + len, BUFFER_ALLOCSZ) <= BUFFER_MAX_LEN)
154: return (1);
155: return (0);
1.1 deraadt 156: }
157:
158: /* Returns the number of bytes of data in the buffer. */
159:
1.9 markus 160: u_int
1.32 djm 161: buffer_len(const Buffer *buffer)
1.1 deraadt 162: {
1.2 markus 163: return buffer->end - buffer->offset;
1.1 deraadt 164: }
165:
166: /* Gets data from the beginning of the buffer. */
167:
1.22 djm 168: int
169: buffer_get_ret(Buffer *buffer, void *buf, u_int len)
1.1 deraadt 170: {
1.22 djm 171: if (len > buffer->end - buffer->offset) {
172: error("buffer_get_ret: trying to get more bytes %d than in buffer %d",
1.11 markus 173: len, buffer->end - buffer->offset);
1.22 djm 174: return (-1);
175: }
1.2 markus 176: memcpy(buf, buffer->buf + buffer->offset, len);
177: buffer->offset += len;
1.22 djm 178: return (0);
179: }
180:
181: void
182: buffer_get(Buffer *buffer, void *buf, u_int len)
183: {
184: if (buffer_get_ret(buffer, buf, len) == -1)
185: fatal("buffer_get: buffer error");
1.1 deraadt 186: }
187:
188: /* Consumes the given number of bytes from the beginning of the buffer. */
189:
1.22 djm 190: int
191: buffer_consume_ret(Buffer *buffer, u_int bytes)
192: {
193: if (bytes > buffer->end - buffer->offset) {
194: error("buffer_consume_ret: trying to get more bytes than in buffer");
195: return (-1);
196: }
197: buffer->offset += bytes;
198: return (0);
199: }
200:
1.6 markus 201: void
1.9 markus 202: buffer_consume(Buffer *buffer, u_int bytes)
1.1 deraadt 203: {
1.22 djm 204: if (buffer_consume_ret(buffer, bytes) == -1)
205: fatal("buffer_consume: buffer error");
1.2 markus 206: }
1.1 deraadt 207:
208: /* Consumes the given number of bytes from the end of the buffer. */
209:
1.22 djm 210: int
211: buffer_consume_end_ret(Buffer *buffer, u_int bytes)
212: {
213: if (bytes > buffer->end - buffer->offset)
214: return (-1);
215: buffer->end -= bytes;
216: return (0);
217: }
218:
1.6 markus 219: void
1.9 markus 220: buffer_consume_end(Buffer *buffer, u_int bytes)
1.1 deraadt 221: {
1.22 djm 222: if (buffer_consume_end_ret(buffer, bytes) == -1)
1.5 markus 223: fatal("buffer_consume_end: trying to get more bytes than in buffer");
1.2 markus 224: }
1.1 deraadt 225:
226: /* Returns a pointer to the first used byte in the buffer. */
227:
1.14 stevesk 228: void *
1.32 djm 229: buffer_ptr(const Buffer *buffer)
1.1 deraadt 230: {
1.2 markus 231: return buffer->buf + buffer->offset;
1.1 deraadt 232: }
233:
234: /* Dumps the contents of the buffer to stderr. */
235:
1.6 markus 236: void
1.32 djm 237: buffer_dump(const Buffer *buffer)
1.1 deraadt 238: {
1.20 markus 239: u_int i;
1.15 stevesk 240: u_char *ucp = buffer->buf;
1.2 markus 241:
1.13 markus 242: for (i = buffer->offset; i < buffer->end; i++) {
243: fprintf(stderr, "%02x", ucp[i]);
244: if ((i-buffer->offset)%16==15)
245: fprintf(stderr, "\r\n");
246: else if ((i-buffer->offset)%2==1)
247: fprintf(stderr, " ");
248: }
1.12 markus 249: fprintf(stderr, "\r\n");
1.1 deraadt 250: }
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